Reducing Image Size With Gimp

Gimp Image Resizing

If your wondering why you would want to reduce image file sizes, there are a couple of reasons. Firstly large image sizes cause slow page load times, so images should be no larger than necessary. Also web interfaces for uploading images often have a maximun file size, so you may actually NEED to resize your images to be able to upload them at all.

For image manipulation there are some great free programs out there. Currently I use Gimp, so I'll show you how to use this to reduce image file sizes.

When you've taken the photo you may have held the camera on it's side to take a portrait shot so when you first open the image up in Gimp it may be necessary to rotate the image- see below - In the main menu select Image / Transform / and rotate 90° clockwise or anticlockwise as necessary.


Gimp Rotate Image

You'll notice next to the image name at the top of the Gimp window it gives the image size in pixels. The image of Princess my cat that I've used here measures 3072x2304px (Pixels) straight out of the camera. This is about 2.5X wider than my laptop, and the maximumn width that the image may be used at will be about 600px, so the file size of this image can be reduced a great deal by scaling the image down in size.

In the main menu select Image / Scale Image.


Gimp Scale Image

In the image scale dialogue box enter the new width. In this case I resized to 600px wide. If you click in the height setting it should automatically scale to keep the images aspect ratio. If it doesn't you can use the link symbol to the right of the width and height boxes to keep width and height linked or unlinked.


Gimp Scale Image Select Size

After scaling the image, now save it in a light weight format, I usually use the .jpg format. In Gimp the save feature in the file menu will only save to the native Gimp format, so to save as a .jpg file use export as shown below.


Gimp Export

On exporting the image you will be given the option to reduce the quality of the image to further reduce the image size. The quality you select may depend on the detail within the image, but in general a small reduction in image quality will not produce a noticable difference and will further reduce the file size of the image.